Would you please tell me more about the nature of OAA and OALA? Are they contributory?

Welcome.

Thanks for answering me.

No, they are non-contributory. OAA is designed to provide a monthly allowance on a non-means-tested basis to Hong Kong residents who are 70 years of age or above to meet their special needs arising from old age. OALA is to provide a special allowance per month to supplement the living expenses of Hong Kong residents aged 65 or above who are in need of financial support and having income and assets not exceeding the prescribed limits.